Flush entrance hemostasis valve with unobstructed passageway

ABSTRACT

A method of placing a catheter into a patient while preventing disadvantageous escape of fluid from the patient comprises providing a catheter secured to a valve hosing. The catheter has a proximal end, a distal end and an interior lumen. The valve housing has a first port, a second port, and a fluid path running between the first and second ports. The catheter and the valve housing have a hollow needle extending therethrough. The method further comprises piercing the patient&#39;s skin, thereby inserting the catheter into the patient. The method further comprises holding the catheter and valve housing in place while removing the hollow needle through the catheter and valve housing. The hollow needle passes through the first and second ports of the valve housing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 12/368,634, filed on Feb. 10, 2009 now U.S. Pat. No. 8,123,727 which is a continuation of U.S. patent application Ser. No. 11/387,469, filed Mar. 23, 2006 now ababndoned, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates generally to catheters used in medical treatments, and specifically to an over-the-needle catheter with a hemostasis valve that restricts blood flow in the absence of an attached medical component.

DESCRIPTION OF THE RELATED ART

In the medical field it is often necessary to insert a catheter into a portion of the human body to withdraw fluids from, or deliver fluids to, the patient undergoing treatment. For example, one method of catheter insertion involves an “over-the-needle” catheter. In an over-the-needle catheter, a needle is positioned within a catheter lumen which is configured to fit snugly around the needle. After an over-the-needle catheter is inserted into the patient's vascular system, the needle is withdrawn, leaving the catheter in place.

One significant problem with this method of implanting a catheter in the bloodstream of a patient is the tendency of blood to flow from the bloodstream through the catheter upon removal of the needle, stylet, trocar, or guidewire used in the procedure of piercing the body and placing of the catheter therein. Once the passageway between the bloodstream and the catheter opening is opened, blood tends to flow out of the body. Additionally, removal of a medical component (such as an intravenous fluid line) from the proximal end of an inserted catheter permits blood to flow from the patient out of the catheter. Such blood flow out of the patient is an undesirable result as it well-recognized in the industry. It is therefore desirable to have a device which seals an over-the-needle catheter from fluid flow in one or both directions upon removal of the needle, stylet, trocar, or guidewire. Such devices are commonly referred to as “hemostasis valves.”

Many solutions to the above-stated problem have been suggested. For example, U.S. Pat. No. 5,405,323 teaches a catheter check valve assembly which incorporates a duckbill valve and a manually operable separator. U.S. Pat. No. 4,449,693 discloses a valve of resilient tubing into which a stopper having an oval sealing ring is placed. U.S. Pat. No. 5,073,168 teaches a y-adapter with a check valve formed from conformable sheets. U.S. Pat. Nos. 5,112,301; 5,156,600 and 5,167,636 also teach other types of catheter check valves and hemostasis valves.

Some existing bi-directional hemostasis valves rely on a differential fluid pressure across a membrane to seal the catheter from fluid flow. This will unfortunately not solve the problem of accidentally disconnected medical component connections, as blood pressure is typically higher than atmospheric air pressure, thus causing blood to leak from such a valve in the absence of a second fluid. Other hemostasis valves described in the above-mentioned patents generally share the disadvantage that they require conscious action of the operator to fully close the valve and seal the cannula from allowing blood to flow out of a patient. This extra step can be forgotten, thus leaving the catheter open to unwanted fluid flow.

Therefore, it is desirable to have a hemostasis valve for an over-the-needle catheter which will always be closed when the medical component is removed, and which requires no extra movement of parts and no extra user actions to further seal the catheter. It is also desirable to have a hemostasis value that is inexpensive to manufacture, that is simple to operate, and that presents a flat surface to facilitate, for example, effective disinfection.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a method of placing a catheter into a patient while preventing disadvantageous escape of fluid from the patient comprises providing a catheter secured to a valve housing. The catheter has a proximal end, a distal end and an interior lumen. The valve housing has a first port, a second port, and a fluid path running between the first and second ports. The catheter and the valve housing have a hollow needle extending therethrough. The method further comprises piercing the patient's skin, thereby inserting the catheter into the patient. The method further comprises holding the catheter and valve housing in place while removing the hollow needle through the catheter and valve housing. The hollow needle passes through the first and second ports of the valve housing.

According to another aspect of the present invention, a method of opening a hemostasis valve comprises providing a hemostasis valve housing. The hemostasis valve housing has a first port, a second port, and a fluid path running between the first and second ports. The method further comprises positioning an occlusion assembly within the hemostasis valve housing. The occlusion assembly has a pivot pin in contact with first and second occlusion arms. The occlusion assembly is movable between a closed position and an open position. In the closed position, the first and second occlusion arms contact each other, causing the hemostasis valve housing first port to be occluded. In the open position, the first and second occlusion arms do not contact each other, allowing fluid flow through the hemostasis valve housing first port. The method further comprises moving the occlusion assembly between the closed position and the open position by sliding the occlusion arms along opposite sides of the pivot pin.

According to another aspect of the present invention, a hemostasis valve comprises a valve housing having a first port, a second port opposite the first port, and a fluid path running between the first and second ports. The hemostasis valve further comprises an occlusion assembly disposed within the hemostasis valve. The occlusion assembly has a pivot pin in contact with first and second occlusion arms, such that the first and second occlusion arms contact opposite sides of the pivot pin. The occlusion assembly is movable between a closed position and an open position. In the closed position, the first and second occlusion arms contact each other, causing the valve housing first port to be occluded. In the open position, the first and second occlusion arms do not contact each other, allowing fluid flow through the valve housing first port.

According to another aspect of the present invention, a hemostasis valve comprises a valve housing having a first port, a second port opposite the first port, and a fluid path running between the first and second ports. The hemostasis valve further comprises means for opening the fluid path when a medical component is attached to one of the valve housing ports, and occluding the fluid path when the medical component is removed from the valve housing port.

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus summarized the general nature of the invention and its essential features and advantages, certain preferred embodiments and modifications thereof will become apparent to those skilled in the art from the detailed description herein having reference to the figures that follow, of which:

FIG. 1 is a side sectional view of one embodiment of a hemostasis valve in the closed position.

FIG. 2 is a side sectional view of the hemostasis valve of FIG. 1 in the open position.

FIG. 3 is a perspective side sectional view of the hemostasis valve of FIG. 1 in the closed position.

FIG. 4 is a side sectional view along cross-section 4-4 of the hemostasis valve of FIG. 1 in the closed position.

FIG. 5 is a side sectional view of one embodiment of a hemostasis valve configured for use with an over-the-needle catheter.

FIG. 6 is an exploded side view of a hemostasis valve having an occluder control arm.

FIG. 7 is an exploded perspective view of the hemostasis valve of FIG. 6.

FIG. 8 is another exploded perspective view of the hemostasis valve of FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 through 4 illustrate one embodiment of a hemostasis valve 100 for use with an over-the-needle catheter having features and advantages of the present invention. The hemostasis valve 100 comprises a valve housing 110 configured to allow fluid to flow along fluid path 116 between a first port 112 and a second port 114. The first port 112 is fitted to allow a medical component 102 (illustrated in FIG. 2) to be removably attached thereto, and the second port 114 is fitted to allow a catheter hub (not shown) to be secured thereto. The hemostasis valve 100 further comprises an occluder 120 positioned within the valve housing 110 that is movable between an open position 122 (illustrated in FIG. 2) and a closed position 124 (illustrated in FIG. 1). In such embodiments, when the occluder 120 is in the open position 122, fluid may flow along fluid path 116 between the first port 112 and the second port 114. When the occluder 120 is towards the closed position 124, fluid path 116 is occluded, thereby preventing the flow of fluid between the first port 112 and the second port 114. In such embodiments, the occluder 120 is biased in the closed position 124, such that when the medical component 102 is attached to the first port 112, a force 126 is applied to the occluder 120, which causes the occluder to move to the open position 122 and thereby permits fluid flow through the valve housing 110. Likewise, when the medical component 102 is removed from the first port 112, the occluder 120 returns to the closed position 124 and thereby prevents fluid flow through the valve housing 110.

In certain embodiments, the valve housing 110 is preferably substantially cylindrical and hollow, thereby providing a fluid path 116 along a central axis 130 between the first port 112 and the second port 114. The fluid path 116 not only allows fluid to pass between the first port 112 and the second port 114, but it also allows a needle (not shown) to be passed through the entire valve housing 110. Such passage of a needle allows the hemostasis valve 100 disclosed herein to be advantageously used in connection with an over-the-needle catheter.

As illustrated in FIG. 2, the first port 112 of the valve housing 110 is fitted to be removably attached to a medical component 102. In certain embodiments, the attachment mechanism is by means of a threading mechanism 118 (for example, a screw-on screw-off mechanism such as a luer lock), although in other embodiments, the removable attachment mechanism may comprise a snap-fit configuration, a latching configuration, or any other removable attachment mechanism. Likewise, the second port 114 of the valve housing is fitted to securely attach to a catheter hub (not shown) by means of a threading mechanism 118 or any other attachment mechanism.

In certain embodiments, the valve housing 110 is preferably comprised of a molded biocompatible polycarbonate material, although in other embodiments, the valve housing 110 is comprised of any other material suitable for use in medical applications, and capable of providing the features and advantages of the present invention.

As illustrated in FIGS. 1 through 4, in certain embodiments, the occluder 120 further comprises first and second occluder shafts 154, 156 which connect first and second occluder proximal portions 150, 152 with occluder distal ring 158. The occluder 120 is preferably comprised of a flexible biocompatible polycarbonate material, such as acrylonitrile-butadiene-styrene (ABS) or polyvinyl chloride (PVC), although other materials, including silicon-based materials, may also be used. In particular, the material comprising the occluder 120 is preferably sufficiently flexible such that when the occluder 120 is in the closed position 124, the hollow needle 106 (illustrated in FIG. 5) can pass between the first and second occluder proximal portions 150, 152 without allowing fluid to leak from the first port 112. In a preferred embodiment, the first and second occluder proximal portions 150, 152 further comprise a seal cap 159 comprising a silicone or rubber material. Seal cap 159 is configured to facilitate the hollow needle 106 passing through the first and second occluder proximal portions 150, 152 without allowing fluid to leak from the first port 112. Seal cap 159 preferably comprises a material different than the material comprising the occluder proximal portions 150, 152.

In such embodiments, the first and second occluder proximal portions 150, 152 are shaped to fit together to occlude the first port 112 completely. For example, in embodiments wherein the first port 112 has a circular cross-sectional shape of diameter d, the first and second occluder proximal portions 150, 152 can each be in the shape of a half-circle of diameter d. Thus, in such embodiments, when the occluder 120 is in the closed position 124 (that is, when the proximal occluder ends 134 are positioned within the first port 112), the first port 112 is completely occluded, thereby preventing the flow of fluid therethrough.

In such embodiments, the first and second occluder shafts 154, 156 have a rectangular cross section, although in alternative embodiments other cross sectional shapes, such as circles, ovals, or other polygons may be used. Notably, the first and second occluder shafts 154, 156 do not extend around the circumference of the valve housing 110, unlike the occluder distal portion 158 and the occluder proximal portions 150, 152. This configuration is illustrated in FIG. 1, which illustrates that the occluder proximal portions 150, 152 and the occluder distal portion 158 extend to the interior wall of the valve housing 110. In contrast, FIG. 4 illustrates that the first shaft 154 (like the second occluder shaft 156, which is not shown in FIG. 4) is a structural arm that functions to transmit forces between the occluder distal portion 158 and the occluder proximal portions 150, 152.

The occluder distal ring 158 is preferably a substantially cylindrical ring configured to slide along the interior walls of the valve housing 110 in a direction indicated by arrows 160. As described above, the first and second occluder shafts 154, 156 are configured to transmit a force 126 applied to the first and second occluder proximal portions 150, 152 to the occluder distal ring 158, such that a force 126 applied to the first and second occluder proximal portions 150, 152 causes the occluder 120 to move distally in a direction indicated by arrows 160.

As illustrated in FIGS. 1 though 4, in certain embodiments, seal guide pins 140 (also referred to as “pivot pins” or “guide pins”) are positioned between the first and second occluder shafts 154, 156. In such embodiments, the seal guide pins 140 are securely attached to the inner walls of the valve housing 110, and gap 142 (as illustrated in FIG. 4) exists between seal guide pins 140 to allow a needle to pass through the center of the valve housing 110. FIG. 5 illustrates one embodiment of seal guide pins 140 and occluder 120 positioned within valve housing 110. In such embodiments, the seal guide pins 140 are preferably comprised of a rigid material such as stainless steel, although in other embodiments the seal guide pins 140 are comprised of any other rigid, biocompatible material suitable for use in medical applications.

As explained above, the occluder distal ring 158 is configured to slide along the inner walls of the valve housing 110 in a direction indicated by arrows 160. As the occluder distal ring 158 slides toward the second port 114, the first and second occluder proximal portions 150, 152 move distally from the first port 112 and are pivoted radially away from the central axis 130 (illustrated in FIG. 2) due to the placement of the seal guide pins 140. Specifically, as the occluder distal ring 158 slides towards the second port 114, the first and second occluder shafts 154, 156 slide/roll along opposite sides of the seal guide pins 140. The seal guide pins 140 act as a fixed control surface pivot point, forcing the first and second occluder shafts 154, 156 to move radially away from the central axis 130, thereby opening fluid path 116. In such a configuration (that is, when the occluder 120 is in the open position 122 as illustrated in FIG. 2), fluid may pass between the first port 112 and the second port 114 along fluid path 116 between the guide pins 140. Preferably, the first and second occluder shafts 154, 156 and the seal guide pins 140 are manufactured of materials capable of sliding with respect to each other with low frictional losses. The first and second occluder shafts 154, 156 and the seal guide pins 140 may also be lubricated.

Likewise, as the occluder distal ring 158 slides toward the first port 112, the first and second occluder proximal portions 150, 152 are guided into the first port 112 due to the funnel neck portion 144 of the valve housing 110. When the occluder 120 is in the closed position 124 as illustrated in FIG. 1, the first port 112 is occluded, thereby precluding fluid flow between the first port 112 and the second port 114 along fluid path 116.

The occluder 120, which is movable between the open position 122 and the closed position 124, is preferably biased towards the closed position 124. As illustrated in FIGS. 1 through 4, the occluder 120 is biased in closed position 124 due to the presence of spring 170 positioned within the valve housing 110. Thus, when a force 126 is applied to the first and second occluder proximal portions 150, 152, the spring 170 compresses and the occluder 120 moves to the open position 122, as illustrated in FIG. 2. Similarly, when the force 126 is removed from the first and second occluder proximal portions 150, 152, the spring 170 and the funnel neck portion 144 of the body 110 causes the occluder 120 to return to the closed position 124, as illustrated in FIG. 1. In such embodiments, the spring 170 is preferably comprised of stainless steel, although in other embodiments the spring 170 is comprised of any other biocompatible material suitable for use as a spring in medical applications, and which will not lose resiliency after repeated uses.

In a preferred embodiment, illustrated in FIG. 2, medical component 102 is removably attached to the valve housing 110 via threading mechanism 118. In such embodiments, as medical component 102 is threaded onto the valve housing 110, actuator element 104 applies a force 126 to the first and second occluder proximal portions 150, 152, causing the occluder 120 to move to the open position 122, and permitting fluid flow along fluid path 116. Likewise, when medical component 102 is removed from the valve housing 110, the spring 170 causes the occluder 120 to return to the closed position 124, wherein the first and second occluder proximal portions 150, 152 occlude fluid flow along fluid path 116. One of ordinary skill in the art will recognize that the medical component 102 can be attached to the valve housing a variety of attachment means, such as a conventional luer lock or by use of friction if a tapered syringe luer fitting is used. Suitable medical components 102 include, but are not limited to, syringes, feeding or hydrating bags, intravenous drip bags, or other tubing, conduits or catheters.

In other embodiments, as illustrated in FIG. 5, the hemostasis valve 100 is available prepackaged with an over-the-needle catheter 132 secured to the second port 114. The over-the-needle catheter 132 can be attached to the second port 114 by a wide variety of means, such as by a threaded luer lock configured to engage an over-the-needle catheter having two threading tabs (commonly referred to as “rabbit ears”). In such embodiments, before the over-the-needle catheter 132 is inserted into the patient, the proximal end of the hollow needle 106 is positioned to pass through the valve housing 110 and between the first and second occluder proximal portions 150, 152 (which are in the closed position 124), where the proximal end of the hollow needle 106 is anchored in needle anchor assembly 108. Specifically, the presence of the gap 142 between the seal guide pins 140, as illustrated in FIG. 4, allows the hollow needle 106 to be passed through the entire length of the valve housing 110, and through the catheter 132. As will be understood by those of ordinary skill in the art, the hollow needle 106 will extend distally through the catheter 132, and will protrude from the distal end of the catheter 132 to allow the introduction of the catheter 106 into a patient.

Once the over-the-needle catheter 132 is inserted into the patient's vascular system, blood will begin to flow through the hollow needle 106, and may fill a transparent flashback chamber (not shown) in the anchor assembly 108, thereby indicating to the user that the catheter is properly placed. Then, the user can withdraw the hollow needle 106 from the over-the-needle catheter 132 by unscrewing the catheter assembly 108 and pulling on finger grips 134 while holding the valve housing 110 in place. As the hollow needle 106 is withdrawn from the over-the-needle catheter 132, blood will begin to fill the over-the-needle catheter 132. As described above, the presence of the gap 142 between the seal guide pins 140, as illustrated in FIG. 4, allows the hollow needle 106 to be withdrawn through the valve housing 110 in a continuous, one-motion fashion. As the distal end of the hollow needle 106 is withdrawn through the hemostasis valve 100, blood will fill the valve housing 110, but will be prevented from flowing out of the valve housing 110 due to the occluder 120 being in the closed position 124. Thus, the hollow needle 106 can be completely withdrawn from the hemostasis valve 100 without allowing any blood to leak from the patient or from the hemostasis valve 100 into the external environment. Additionally, this configuration eliminates the need for the user to “pinch off” the blood flow from the over-the-needle-catheter 132 during withdrawal of the hollow needle 106, as is required when using conventional other-the-needle catheters.

FIGS. 6 through 8 illustrate an alternative embodiment of a hemostasis valve 200 that does not include a seal guide pin, thus reducing manufacturing costs. As illustrated, the modified hemostasis valve 200 comprises a hollow valve housing 210, an occluder 220, a spring 270, and a seal guide arm assembly 280. The seal guide arm assembly 280 preferably comprises two seal guide arms 284 ending in pivot points 282, although in other embodiments, the seal guide arm assembly 280 can comprise a different number of seal guide arms 284.

The seal guide assembly 280 serves the same function as the seal guide pins (described above), while being easier and less expensive to manufacture. In particular, the seal guide arm assembly 280 provides pivot points 282 over which the first and second occluder shafts 254, 256 slide as the occluder 220 moves within the valve housing. In such embodiments, the seal guide arms 284 are adjacent to an unoccupied region along a central axis of the hemostasis valve 200, thereby allowing a hollow needle (not shown) to be passed through the hemostasis valve 200. Preferably, the occluder 220 is modified to include slots 286 configured to accommodate the seal guide arms 284.

In any of the embodiments of the hemostasis valve described herein, after the hollow needle 106 and needle anchor assembly 108 have been removed from the catheter and valve housing 110, other medical components 102 configured to remove blood from, or supply fluids to, the patient can be attached to the first port 112 of the valve housing 110. As discussed above, placement of a medical component 102 on the first port 112 will cause the occluder 120 to move to the open position 122, thereby providing access to the patient via the over-the-needle catheter 132. In alternative embodiments, the valve housing 110 and the over-the-needle catheter 132 are formed into one component, such that the hemostasis valve 100 is integral with of the over-the-needle catheter 132.

The embodiments described herein ensure that the hemostasis valve 100 is closed whenever no medical component 102 is secured to the first port 112. Whenever medical component 102 is removed from the first port 112, either accidentally or intentionally, the restoring force of the spring 170 preferably causes the occluder 120 to return to the closed position 124. This configuration prevents blood from disadvantageously leaving the body via the over-the-needle catheter 132.

Additionally, when medical component 102 is removed from the first port 112, the proximal portions of first and second occluder proximal portions 150, 152 are exposed, thereby allowing the hemostasis valve 100 to be swabbed between uses. This configuration allows a single over-the-needle catheter 132 to be used for a plurality of different treatments once the over-the-needle catheter 132 has been inserted into the patient. Furthermore, by using this configuration, fluids are easily infused to, and fluids are easily withdrawn from, the patient's vascular system.

One of ordinary skill in the art will recognize that the hemostasis valve described herein is not limited to use in conjunction with a patient's vascular system. In particular, the various embodiments of the hemostasis valve described herein can be used at a wound or surgical site by placing the over-the-needle catheter 132 into the patient's body at such a site.

Scope Of The Invention

The above presents a description of a preferred embodiment for the present hemostasis valve for use with an over-the-needle catheter, and of the manner and process of making and using it, in such full, clear, concise and exact terms as to enable any person skilled in the art to which it pertains to make and use this hemostasis valve for use with an over-the-needle catheter. This hemostasis valve for use with an over-the-needle catheter is, however, susceptible to modifications and alternate constructions from that discussed above which are fully equivalent. Consequently, it is not the intention to limit this hemostasis valve for use with an over-the-needle catheter to the particular embodiments disclosed. On the contrary, the intention is to cover all modifications and alternate constructions coming within the spirit and scope of the hemostasis valve for use with an over-the-needle catheter as generally expressed by the following claims, which particularly point out and distinctly claim the subject matter of the hemostasis valve for use with an over-the-needle catheter. 

We claim:
 1. A hemostasis valve comprising: an elongate valve housing having a first port, a second port opposite the first port and a fluid path running between the first and second ports which is aligned to a longitudinal axis of the valve housing, the valve housing having a cylindrical straight portion and a conical portion; an occluder slideable within the housing between first and second positions, the occlunder having: a structural occluder ring slideable against the interior surface of the cylindrical straight portion of the elongate valve housing; a plurality of structural occlusion shafts each having distal end portion connected to the structural occlude ring and a free end portion; the free end portions of the occlusion shafts slideable against the interior surface of the conical portion of the elongate valve housing, the free end portions collectively forming a plug configured to fit within the first port to occlude the first port when the occluder is in the first position, the proximal end portions being closer to the first port than the structural occluder ring; wherein the structural occlusion shafts are forced apart from each other when the occluder is in the second position to spread open the proximal end portions of the occlusion shafts and allow fluid to flow through the first port.
 2. The valve of claim 1 wherein the plug has a circular configuration and the first port has a circular configuration.
 3. The valve of claim 1 further comprising a pin attached to the housing, and wherein the structural occlusion shafts include first and second shafts, the first shaft disposed on a first side of the pin and the second shaft disposed on a second side of the pin opposite the first side.
 4. The valve of claim 1 further comprising a biasing member disposed within the housing between the structural occluder ring and the second port for biasing the occluder to the first position.
 5. The valve of claim 1 wherein the interior surface of the valve housing has a funnel neck configuration which guides the free end portions of the structural occlusion shafts within the port as the structural occluder ring is traversed to the first position from the second position.
 6. The valve of claim 1 wherein the occluder is separate from the valve housing so that the occluder slides within the housing as a single unit.
 7. The valve of claim 1 further comprising a pin with opposed ends of the pin attached to the interior surface of the elongate valve housing, the plurality of structural occlusion shafts being disposed on opposed sides of the pin to force open the structural occlusion shafts as the occluder is traversed from the first position to the second position.
 8. The valve of claim 7 wherein the pin further comprises a pathway aligned to the first port and the second port to allow a hollow needle to pass through the first and second ports independent of whether the occluder is in the first or second positions.
 9. The valve of claim 8 wherein the pathway of the pin is a hole aligned to the longitudinal axis of the valve housing.
 10. The valve of claim 1 wherein unobstructed flow from the first port to the second port is provided when the structural occlusion shafts are spread open.
 11. A method of operating a hemostasis valve comprising the steps of; providing a hemostasis valve with a first port with free end portions of structural occlusion shafts in a first position which occlude the first port; sliding free end portions of the structural occlusion shafts against a conical internal surface of a housing of the valve and in a direction away from the first port and toward a second port of the hemostasis valve to a second position with a medical component to facilitate fluid flow through the valve, the first and second ports defining a longitudinal axis; sliding a rigid occluder ring against a straight cylindrical surface of the housing of the valve simultaneously with the sliding free end portions step; attaching the medical component to the valve housing adjacent to the first port.
 12. The method of claim 11 further comprising the step of providing an unobstructed flow path from the first port to the second port when the free end portions of the structural occlusion shafts are spread open.
 13. The method of claim 11 further comprising the step of biasing the structural occlusion shafts toward the first port. 